The invention relates to a device for manufacturing, filling and sealing sacks as disclosed in the preamble of claim 1.
Such a device is disclosed, for example, in the DE 93 01 355 U. This document describes a class of device for manufacturing, filling and sealing thermoplastic sacks that are open on one side and have preferably side folds. This device comprises a first welding and severing station for forming the sack with a bottom weld, a filling station and a second welding station for sealing the sack. Here is a first pair of gripping pliers as the pair of transport gripping pliers for accepting the sack at the first welding station; a second pair of gripping pliers that are arranged stationarily at the filling station; and a third pair of gripping pliers as the pair of transport gripping pliers that transport the sack from the filling station to the second welding station. The DE 93 01 355 U has already managed to increase the timing rate, since a stationary pair of grippers is provided in the area of the filling station so that the sack can be held for filling in the filling station, while the other transport grippers can already carry out their lifting motion to accept new sacks.
The EP 0 468 376 B2 also discloses this class of device, which is designed to reduce the transversal distance between the individual processing stations and thus reduce the overall length of the device. To this end, the pairs of gripping pliers are moved vertically up and down through the vibratory motions of an eccentric in the region of the acceptance or delivery of sacks in order to be able to pick up the sack by its edge without having to swing the pair of gripping pliers at an opening angle of 180xc2x0. Since the pairs of gripping pliers must be swung completely open in order to accept sacks, it is necessary to provide a comparatively large amount of space inside the device, which opposes any reduction in the overall length.
The object of the invention is to improve this class of device so that the processing rate of the machine is increased and at the same time the entire device can be built more compactly.
The invention solves this problem with the features of claim 1. According to the characterizing features of claim 1, a fourth pair of gripping pliers is provided as the pair of transport gripping pliers that accepts the sack from the first pair of transport gripping pliers through the in-line arrangement of a stationary pair of gripping pliers and delivers to the pair of gripping pliers, which are arranged stationarily at the filling station. The fourth pair of gripping pliers assumes a delivery position to deliver the sack to the pair of gripping pliers that is arranged stationarily at the filling station and lies in a plane that is higher by a distance (x) than its acceptance position for the sack.
This arrangement makes it possible for a compact and space saving construction of the stationary pair of gripping pliers, especially in the area of the filling station, where owing to the plurality of components, like the various pairs of pliers, for example the additional suction mechanism for opening the sacks.
In contrast to the prior art, there is no need to pull this pair of gripping pliers vertically to the top in order to pick up the end of the sack. Rather this stationary pair of gripping pliers can be arranged stationarily. A relatively small opening angle is sufficient, since owing to the higher delivery position the upper end of the sack can be passed by the additional fourth pair of gripping pliers from the below into the pickup space formed between the stationary pairs of gripping pliers.
Other especially preferred embodiments follow from the dependent claims following the main claim.
The advantageous result of the coupling motion of the pairs of gripping pliers, as disclosed in the features of the dependent claims, is that the fourth pair of gripping pliers can be moved so as to lead the first and third pair of gripping pliers, which are coupled together in their motion so that the timing rate can be further improved due to the improved acceptance management of the sacks.